As a scheme for changing a total magnification at which samples are magnified for observation, microscopes conventionally adopt various schemes such as switching of an objective lens and the use of a zoom lens.
For example, in the scheme of switching the objective lens, a lens revolver with a plurality of objective lenses of different magnifications installed therein is utilized to switch the objective lens inserted into an observation optical path. Thus, the magnification can be intermittently changed simply by rotating the lens revolver. Furthermore, in the scheme utilizing the zoom lens, the magnification can be linearly changed by consecutively moving the zoom lens in a zoom ring provided that the zoom lens is moved within the movable range thereof.
Additionally, in a microscope including a lens revolver or a zoom lens, the operability of the microscope can be improved by electrically driving rotation of the lens revolver or movement of the zoom lens.
In particular, in many cases, a stereoscopic microscope with which a user observes biological samples intact uses both the scheme of switching the objective lens and the scheme utilizing the zoom lens. The stereoscopic microscope thus enables linear changes in magnification and allows widening of the range within which the magnification can be varied.
For example, Patent Literature 1 discloses a microscope system including an objective switching mechanism configured to electrically switch the objective lens and a zoom mechanism configured to move the zoom lens.
Furthermore, Patent Literature 2 discloses a technique to detect the rotation direction of the revolver when the revolver is rotated, to predict which of the objective lenses the current one is to be switched to.